Rotary switch having torsion bar type return spring



Nov. 19, 1968 P. A. MEDICKS ET AL 3,411,375

ROTARY SWITCH HAVING TORSION BAR TYPE RETURN SPRING Filed Feb. 5, 1967 2 Sheets-Sheet 1 PRIOR NOV. 19, 1968 P cKs ET AL 3,411,375 1 ROTARY SWITCH HAVING TORSION BAR TYPE RETURN SPRING Filed Feb. 3, 1967 2 Sheets-Sheet 2 United States Patent Office 3,411,375 Patented Nov. 19, 1968 3,411,375 ROTARY SWITCH HAVING TORSION BAR TYPE RETURN SPRING Peter A. Medicks and Earl E. Schwarzenbach, Smithfield, N.C., assignors to Shallcross Manufacturing Company, Selma, N.C.

Filed Feb. 3, 1967, Ser. No. 613,932 4 Claims. (Cl. 74-504) ABSTRACT OF THE DISCLOSURE A rotary switch operating mechanism having a torsion bar type return spring, secured at one end in a bore in a rotary operating shaft, and non-rotatably secured at its other end to the switch frame to afford return of the operating shaft to normal position following rotation thereof to one or more switch operating positions.

This invention relates to a novel form of torsion bar spring return mechanism for rotary switches of the two or more position momentary type.

Rotary switches of the momentary type as heretofore constructed have utilized helically coiled twist springs to effect return of the operating shaft from either side, or both sides of a center or off position depending upon the number of switching units or switch decks used. Helically coiled return springs have required a number of coil turns and the overall length of the switch must in part accommodate the length of the return spring. With increasing demand for the number of switch units that can be mounted behind a mounting panel, it is desirable that some means he provided to effect the shaft return not requiring the considerable overall length of the usual helical coil springs. It is therefore an object of the present invention to provide a novel form of torsion return spring which markedly reduces the space required behind the mounting panel for the complete switch mechamsm.

Another object of the invention is to provide an improved form of three position momentary rotary switch embodying the invention.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment of the invention that will be hereinafter described in detail in connection with the accompanying drawings. It is to be understood that the preferred embodiment disclosed is susceptible of modifications with respect to details without departing from the scope of the appended claims.

FIGURE 1 is a side elevational view of a rotary switch of the three position momentary contact type constructed in accordance with prior art practices;

FIG. 2 is a side elevational view of a rotary switch of the aforementioned type constructed in accordance with the present invention;

FIG. 3 is a lateral section taken along line 3-3 of FIG. 2;

FIG. 4 is a bottom plan view;

FIG. 5 is a sectional view taken along the line 55 of FIG. 2; and

FIG. 6 is an exploded view in isometric perspective showing the various parts of the switch of the present invention.

Referring to FIG. 1, it shows a rotary momentary switch 10 having a rotary operating shaft 10a, a ball position detent mechanism, generally designated 10b, and a helical twist return spring 100. It may be assumed that switch 10 is of the three position, center off type having commutating positions on either side of the center position. The ends of the spring 10c bear against an upstanding post 10e on opposite side thereof and also against a downturned tab 10d of a rotor plate 10 which is keyed to a portion of the shaft 100.

Let it be assumed that the shaft 10a is turned to the left as shown in FIG. 1. In that case the tab 10d will move the left-handmost end of spring to the left and thereby cause an increase in spring tension. When rotor 10 is released after obtaining an operating position, the energy stored in spring 100 will return rotor 10 to the position depicted in FIG. 1. Likewise, when rotor 10 is rotated to the right as shown in FIG. 1. The right-hand or lower-most end of spring 100 will be moved by the tab 10dv to the right to compress spring 100 as aforementioned and when released rotor 10f will rotate to the left to bring the rotary shaft back to the position depicted in FIG. 1. Although not shown, it may be assumed that contacts contained in the switch deck 10g are appropriately commutated in either of the aforementioned operating positions. It will be seen that the spring 100 has a number of coil turns and encompasses a considerable overall portion of the total length of the switch 10 below the threaded one-hole mounting boss 10h.

The switch 12 embodying the present invention, shown in FIGS. 2 through 6 comprises a switch deck 14, a rotary operating shaft 16, a combination shaft bearing support and threaded one-hole mounting bushing 18, a position detent mechanism, generally designated 20 and comprising a ball cage plate 22, a ball detent plate 24, detent disc spring 26 and a pair of detent balls 28. Switch 12 further comprises an upper stop pin retaining plate 30 to which the member 18 is mounted by spinning over the bottom surface, a torsion spring assembly generally designated 32, a torsion spring anchor plate 34, upper and lower cover plates 36 and 38, stop pins 40 and switch assembly screws 42.

As shown in FIG. 3, rotor shaft 16 is provided with an axial bore which at its upper end is provided with a portion 16a which merges through a frusto-conical tapered portion 16b to a portion of reduced diameter. A torsion spring assembly 32 comprises a pair of like torsion leaf springs 44, preferably formed of a spring steel, and a plug-like clamp member 48 which has a frustoconical tapered end and a transverse slot formed therein. The springs 44 are inserted in the aforementioned slotted end of member 48 and the assembly inserted into the end of the large portion of the bore in rotor 16 and forced downwardly therein with the serrated portion 48a of a member 48 having an interference with the inner side walls of the portions 16a and 16b of the rotor 16. The walls of slot surrounding the springs are to tightly clamp them in the end of member 48. The springs 44 at their lower ends extend beyond the lower end of rotor shaft 16 and are anchored against rotation in a rectangular slot 34a of complemental dimensions formed in anchor plate 34.

Shaft 16 over the lower half of its length is provided with flats on opposite sides thereof and extends through a complementally formed opening in a rotary contactor 14a within the switch deck 14. The detent disc spring 26 is provided with a clover leaf like cutout portion 26a and a pair of circular openings 26b which are concentric with openings 22d formed in ball cage plate 22. Rivets 50 are inserted through the alined openings in the spring plate 26 and ball cage plate 22 to secure the former to the latter. Shaft 16 extends through a centrally located opening 22a in plate 22 and plate 22 has a number of openings 22c spaced at equal rotary angles about the center and are concentric with corresponding openings in stop pin retaining plate 30.

Detent balls 28 fit within openings 22b in plate 22 and at the lower ends engage the spring plate 26 at tabs 26c. Detent plate 24 is suitably keyed on the lower half of rotor shaft 16 and is provided with openings 24a concentric with, but smaller in diameter than the openings 22b in ball cage plate 23. The upper portions of the balls 28 in the center position of the detent engage within openings 24a. A thrust-washer 52 fits about shaft 16 and between bushing 18 and ball detent plate 24.

The assembly comprising member 18 and stop pin retaining plate 30 fit about the shaft 16 and the screws 42 penetrate openings 30a in plate 30 down through alined notches 22c in plate 22, through openings 14c in the switch deck 14, and through openings 38a in the lower bottom cover plate 38. Nuts 54 take onto the threaded ends of the screws 42 and thereby hold the assembly together. The upper plate 36 has downwardly depending split tangs 36a on opposite sides thereof which are adapted to fit into notches 30b formed in plate 30 and have notches 360 formed therein which engage with the edges of the notches 30b to hold the cover plate in place. Extensions 36d have downwardly depending arms on both sides that overlie the heads of the screws 42.

With the upper cover plate 36 removed, the stop pins 40 may be inverted in any of the openings 300 formed in plate 30 and have portions that fit within the openings 220 in plate 22. This removability of the pins 40 permits adjustment of the angle of rotation of the rotary shaft 16. In the embodiments shown in FIGS. 2 through 6 the pins 40 are spaced suitably to provide a rotation of shaft 16 approximately 30 degrees either side of center position. It will be noted that the rotor plate 24 is provided with a tab 240 which engages with the pins 40 at the end of the angular rotation.

It will be apparent that if rotor shaft 16 is rotated in either direction from its normal or center position, torsion springs 44 will be helically twisted along a longitudinal axis running through the center of the opening 34a and the center of the aforementioned slot in member 48. In so twisting, energy will be stored in the springs 44 which will provide a shaft position restoring force when shaft 16 is released. The aforedescribed ball detent mechanism, of course, provides a definite position feel or indication.

While only one switch deck 14 has been shown in the disclosed embodiment, it will be appreciated that the use of the present invention is not limited to rotary means nonrotatably anchored at one end in the bore of said shaft, and support means spaced from the first mentioned means in which the other end of said spring means is anchored, said shaft upon rotation from a given position efifecting axial helical twisting of said spring means to provide shaft return rotation to said given position upon release thereof.

2. The combination according to claim 1, wherein said torsion bar spring means comprises at least two, elongated, flat spring members which are positioned and secured at corresponding ends within the bore of said shaft to rotate therewith, and which are anchored at their opposite corresponding ends by said means spaced from the first mentioned means.

3. The combination according to claim 2, wherein said torsion bar spring means also comprises a member nonrotatably seated within the bore of said shaft and having a slotted end within which said spring members are secured at their first mentioned corresponding ends.

4. The combination according to claim 3 wherein said means spaced from the first mentioned means comprises a member having an opening alined with and complementally formed to accommodate and hold the opposite corresponding ends of said spring members fixed.

References Cited UNITED STATES PATENTS 2,251,612 8/1941 Kohls et a1. 7410.22 2,404,633 7/1946 Hausler 20070 2,419,986 5/1947 Brown 200- X 2,638,003 5/1953 Lindell 200- X 2,694,319 11/1954 Johnson 74S59 2,777,472 1/1957 Pfarrweller 139145 3,190,983 6/1965 Kesl ZOO-70 3,336,816 8/1967 Medrick et a1 74527 FRED C. MATTERN, JR., Primary Examiner.

C. F. GREEN, Assistant Examiner. 

